<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>$Title$</title>
</head>
<body>
<script type="text/javascript" src="Stack.js"></script>
<script type="text/javascript">
  const stack = new Stack()
  stack.push('abc')
  stack.push(123)
  stack.push(true)
  console.log(stack.peek(), stack.size(), stack.isEmpty()) // true, 3, false
  stack.pop()
  console.log(stack.peek(), stack.size(), stack.isEmpty()) // 123, 2, false
  stack.clear()
  console.log(stack.size(), stack.isEmpty()) // 0, true
</script>
</body>
</html>